Question

Question #4dd1e

Answer 1

`20W`

Explanation:

Let the resistance of each 60W bulb be `ROmega`
When connected in series the combination will have equivalent resistance `=3ROmega`

Power of each lamp `P=60W`

If supply voltage be `E " Volt"` then `"Power"(P)=E^2/R`
`=>60=E^2/R`

When the combination is connected to the mains, then total power consumed by the combination will be

`P_"comb"=E^2/(3R)=1/3xx60W=20W`